U.S. Army Corps Of Engineers Reservoir Release Information

Rapidly changing weather conditions in Montana, northern Wyoming and the western Dakotas have prompted the U.S. Army Corps of Engineers to make adjustments to previously announced reservoir releases. Future releases will reach record levels considerably higher than those previously announced.

Releases from the Missouri River reservoirs, already at historic levels, will be increased again due to higher than forecasted rains in North Dakota yesterday. Record flows and flooding are the result of above-normal snowpack and extraordinary rain events during the last several weeks. Significant flooding in cities, towns and agricultural land is expected in North and South Dakota with many areas from Sioux City, Iowa, to the Mississippi rising above flood stage.

Flows from five of the six dams are expected to reach a record 150,000 cfs by no later than mid-June.  The previous record releases took place in the fall of 1997 at Gavins Point Dam in Yankton, S.D.

“Protecting lives is our number one priority right now,” said Brig. Gen. John McMahon, Commander of the Northwestern Division of the Army Corps of Engineers.  “We are working closely with state and local emergency management teams to identify potential flood areas, provide residents with the most current information and help protect vital public infrastructure.”

People living along the river are encouraged to make evacuation plans to protect their possessions and property. Maps for potential flood areas can be found at: www.nwo.usace.army.mil <http://USACEARMY.pr-optout.com/Url.aspx?520028x528838x503404. Residents in communities along the river are encouraged to contact their local emergency management offices for additional details.

Flooded areas are expected to be inundated for several months.

“Moving water out of the reservoirs is essential,” said General McMahon. “Our release plan is based on the rain we’ve already received and that which is forecast for this weekend and the snow melt forecast. More heavy rain storms could cause major revisions.”

“Due to our vigilant dam safety program, all dams are well prepared to handle the onslaught of floodwaters,” said McMahon. “This is what these reservoirs were designed to do. They are inspected and maintained on rigid schedules. Our dams are sound.”

In the last month, portions of the upper basin have received a year’s worth of rain. “The amount of rain has nearly filled the reservoirs, doing away with the flexibility we had built into our operations for this year,” said Jody Farhat, Chief of the Water Management Division here. “With the arrival of the 140 percent-of-normal snowpack runoff, all the reservoirs will reach their maximum levels, and two will use surcharge storage requiring the operation of the spillways.” Surcharge storage is storage in excess of the exclusive flood control pool. The exclusive flood control pool is the area of the reservoir designed exclusively for the storage of floodwaters.

“Our initial release plans were based on rains already received as well as what’s in the forecast for snowmelt,” said Farhat. “The continuous heavy rains we’re experiencing throughout the basin have dramatically altered our release plans and if we continue to receive heavy rains like this, major revisions in the plan will be necessary.”

Releases out of Fort Peck, Mont., will start to step up next week and are expected to reach 50,000 cfs by June 6.  The reservoir will use several feet of surcharge storage above the exclusive flood control pool as the spillway gates are raised.

Garrison releases will increase from the current 80,000 cfs to 85,000 cfs on Monday and Tuesday, and will quickly be stepped up to 120,000 in early June.  Releases are scheduled to reach 150,000 cfs no later than mid-June. The reservoir will utilize several feet of surcharge storage above the exclusive flood control pool as the spillway gates are raised. For the first time in history, the spillway gates will be used to pass floodwaters at Garrison Reservoir.

Oahe releases will be maintained at the 85,000 cfs rate through June 2 and then quickly stepped up to 130,000 cfs during the first week of June. Releases are scheduled to peak at 150,000 cfs no later than mid-June.  The reservoir will peak within a foot of the top of the spillway gates at 1619 feet.

Big Bend releases will mirror those from Oahe, with its reservoir remaining essentially level at 1420 feet.

Releases from Fort Randall will gradually increase from the current 67,000 cfs to 100,000 cfs during the first week of June. Releases are scheduled to peak at 148,000 cfs no later than mid-June.

Releases from Gavins Point will gradually increase from the current 69,000 cfs to 100,000 cfs during the first week of June. Releases are scheduled to peak at 150,000 cfs no later than mid-June.

“State and local emergency management teams will be the point of contact for residents needing information about flooding in their area,” said Kim Thomas, Chief of the Emergency Management Office here.